Cannabis, which is the most widely used recreational substance in the world, is considered by many consumers as safe with few negative side effects. This opinion is somehow strengthened by the fact that cannabis was also shown to have therapeutic applications. Cannabis is obtained from the plant Cannabis sativa and its varieties Cannabis indica and Cannabis americana. The 2 main preparations derived from cannabis are marijuana and hashish. The principal psychoactive cannabinoid in cannabis is delta 9 tetrahydrocannabinol, and the potency of different preparations of cannabis that relates to tetrahydrocannabinol content is extremely variable. The plasma half-life of tetrahydrocannabinol is ~56 hours in occasional users and 28 hours in chronic users. Psychopharmacological acute effects associated with cannabis use are euphoria, increased self-confidence, relaxation, and a general sense of well being. Except for nausea associated with cancer chemotherapy, most of the potential beneficial effects are not approved by many administrations around the world. Indeed, the more common effects described as beneficial are glaucoma, analgesia, appetite in AIDS patients, tremor, Parkinson disease, spasticity in multiple sclerosis, epilepsia, anxiolytic, or antidepressive actions. However, several important negative side effects associated with cannabis are also observed. Indeed, in selected patients, acute psychiatric and behavioral abnormalities, such as anxiety, panic, and attentional abnormalities, have been reported. Risk of psychotic disorders or symptoms is higher in regular users of cannabis. [Extract]